Excessive blood loss is one of the leading causes of death following severe injury in the battlefield or civilian world. Timely and effective hemorrhage control can not only save victim's lives but also prevent them from post-injury complications and facilitate their wound healing process. Direct pressure at sites of injury by clamping, tourniquet or manual compression in conjunction with medical gauze, has been long used for standard treatment of bleeding wounds on the battlefield. Though many topical hemostatic dressings based on gelatin, collagen and oxidized cellulose have been long used for surgical procedures, they haven't been deployed in the field because of their limited effectiveness in controlling high pressure bleeding. Recently, several new advanced topical hemostats have been developed to treat severe bleeding and deployed for military and civilian emergency use. These include chitosan-based wound dressings.
Chitosan is a derivative of chitin, a naturally occurring biomaterial. There are several advantages by utilizing chitosan as wound dressing material due to its biodegradability, biocompatibility, antibacterial activity, hemostatic activity and bioadhesive property. Chitosan-based wound dressing can be made in a form of powder, film, sheet, patch, sponge, non-woven pad, fabric, mesh, or the like.
Currently there are two physical forms of chitosan-based hemostatic dressings (CELOX™ granules and chitosan bandages) that are commercially available and approved by Food and Drug Administration for temporary hemorrhage control. CELOX™ is lightweight chitosan powder manufactured by MedTrade Products Ltd. The CELOX™ achieves hemostasis by interacting with blood to form a barrier clot at the bleeding site. However, because CELOX™, by nature, has no physical integrity, the powder may be flushed away by ongoing high volume and high pressure bleeding before forming clots. Another disadvantage of CELOX™ is that the manual compression necessary for slowing down blood flow cannot be applied if powder dressing is used alone. Chitosan bandages are a rigid, crystalline chitosan matrix. A combination of its strong adhesive properties and ability to promote clotting makes the bandage effective in controlling severe bleeding when the wounds are open and accessible. However, if the bleeding is from a narrow and deep injury, hemorrhage control by a chitosan bandage may not be effective either because of a difficulty applying the bandage or because of a poor conformity to the injury cavity due to its physical stiffness. Therefore, there is a need to improve the flexibility of chitosan bandages while maintaining or further improving its adhesive properties and hemostatic activity.